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Why Polar Bear Penises Are Getting Weaker, Smaller

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Polar bears are already facing major problems as a result human activity, like in the rapid loss of sea ice due to climate change. But the species' arctic habitat isn't the only thing being diminished by people.

The lingering presence of a now-banned chemical may still be wreaking havoc on polar bears - specifically their penises, according to a new study.

As with many mammals, male polar bears have a bone in their genitalia, called a baculum or penile bone, thought to aid in reproduction by keeping their sex organs rigid while they mate. Researchers tell New Scientist that this part of the species' anatomy could be at risk of breaking because of pollution.

Contaminants known as polychlorinated biphenyls (PCBs), used in industrial production for decades until they were banned by the UN in 2001, have been associated with a number of health problems in animals, including a reduction in the density of baculum. Unfortunately for polar bears, their habitat is where much of the PCBs released have ended up.

"These chemicals enter the atmosphere at lower latitudes where they were used, and are then deposited down from the cold polar air, so Arctic animals are more highly exposed than animals in more temperate or equatorial regions," says University of Florida researcher Margaret James.

The link between high PCB levels and the less-dense baculum found in polar bear specimens is still under investigation, but study author Christian Sonne is concerned that it could cause some painful issues for the animals when it comes to mating.

"If [the baculum] breaks, you probably won't have a bear which can copulate," says Sonne.

PCBs aren't the only potential problem when it comes to polar bear penises. In an earlier study Sonne found that high levels of another industrial chemical group, organohalogens, were linked to a reduction in the size of the bears' sex organs.